I have sentup a hunt group for an external number but when I call it ,it goes throught the list but gets a busy at the 5 entry no matter what extension it is even voice mail?
Sorry about that, I was thinking AA Hunt Groups. Here is what I would look at in your scenario;
Router(config-telephony)# max-redirect x
Sets the number of times that a call can be redirected within a Cisco Unified CME system.
number - Range is 5 to 20. Default is 5.
Note: This command is required if the number of hops is greater than 5. (which yours is :)
Hope this helps!